The vulcanization of diene elastomers by sulphur is widely used in the rubber industry, in particular in the tire industry. Use is made, to vulcanize diene elastomers, of a relatively complex vulcanization system comprising, in addition to sulphur, a primary vulcanization accelerator, such as sulphenamides comprising a benzothiazole ring system, and various secondary vulcanization accelerators or vulcanization activators, very particularly zinc derivatives, such as zinc oxide (ZnO), alone or used with fatty acids.
The sulphenamides comprising a benzothiazole ring system used as primary vulcanization accelerators are, for example, N-cyclohexyl-2-benzothiazolesulphenamide (abbreviated to “CBS”), N,N-dicyclohexyl-2-benzothiazolesulphenamide (abbreviated to “DCBS”), N-tert-butyl-2-benzothiazolesulphenamide (abbreviated to “TBBS”) and the mixtures of these compounds.
Vulcanization accelerators play an important role in the achievement of a delay phase (induction period), that is to say the time necessary for the start of the vulcanization reaction, and it is known to a person skilled in the art that this parameter is very difficult to adjust. It is therefore particularly advantageous for a person skilled in the art to have a vulcanization accelerator which induces a lengthy delay phase, which he can adjust, if desired, by the addition of supplementary accelerators.